The research objective in this proposal is mainly to study age-related changes of 'DNA repair capacity' in a model organism for aging research - the nematode Turbatrix aceti. Both production and excision repair of TT, CT and t' in the DNA of UV irradiated young and old T. aceti will be investigated. Similar studies will be carried out on the production and repair of t' in the DNA of x-ray irradiated young and old T. aceti. These excision repair studies will be complemented with measurements of repair synthesis activities of UV and x-ray irradiated young and old T. aceti. If enzyme alterations do occur in the aging process, then, such alterations should change the 'DNA repair capacity' because DNA repair involves several repair enzymes. This is our working hypothesis for our immediate research objective. The methods that will be used include nematode culture techniques, radiochemical techniques, chromatography (column, paper, thin layer and high pressure liquid chromatography), radioactive counting, gel electrophoresis and other enzymological and biochemical procedures.